Gift for brother's girlfriend?

Hey all!

So I'm on a pretty tight budget because of school and my family and friends know that. For Christmas my brother's girlfriend (who I'm just starting to get to know, so we're not super close yet) got me a very thoughtful gift. She gave me a Starbucks card and a cute coffee travel mug and some holiday hair ties. It was so sweet but I just couldn't afford to get her anything. On top of that I had no idea she was giving me a gift because, like I said, we're not really close yet.

Anyway, she recently got a new job and is so excited about it. It's a big deal for her so I want to do something sweet to congratulate her but I'm still on a tight budget.

She loves Harry Potter and LOTR and lots of the "nerdy" stuff (not an insult, I like that stuff too).

Any ideas?

Thanks ladies!